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By C. E. Lesher

Two processes for agglomerating fine sized ores with low temperature coke are described. One process (Orcarb) agglomerates ores with limited amounts of carbon; the other (ore-carbon pellets) pelletizes fine sized ores, using low temperature cokes as the binder. Data are presented on the products obtained when taconite, magnetite, and hematite concentrates and several titanium oxide ores were used. REDUCTION of finely divided oxide ores has long been a major metallurgical problem. Various methods of agglomerating, notably briquetting, sintering, nodulizing, and pelletizing, have been developed and are in industrial use. Carbon is the usual reducing agent for oxide ores and attempts have been made to agglomerate fine ores with coking coal in order to get the metallurgical advantages of intimate contact and increased particle sizes suitable for subsequent smelting or reduction.1-3 For the past three years, research has been in progress on two processes for combining fine sized ores with reactive carbon in the form of low temperature coke. By one process, designated Orcarb, the ore is coated with coke carbon in amounts limited to that required for reduction and the result is an appreciable but limited increase in product particle size over that of the original ore. The second process, called ore-carbon pellets, produces pellets of fine ore bound by low temperature coke. The first objective was to develop a process for combining an oxide ore with only enough carbon for its reduction, the amount being that derived from the simple reduction equations. The carbon (that amount theoretically required for the reduction of the oxides in an agglomerate with ore), calculated to CO, ranges from 10 pct for zinc calcines Or phosphate Ores to 21 pct for rutile and 26 pct for silica. The carbon required for reducing iron oxides falls between the extremes—10 and 26 pet' When the carbon in the agglomerate is low temperature coke, reduction by hydrogen may be expected to take place, thus modifying the calculated carbon require- ment. On the other hand, in practice, an excess of reducing agent over that required in theory is normally used. Screen sizes of three iron ores on which the greater part of the experimental work was performed are given in Table I. Most of the testing was done with Freeport (Renton Mine) coal, but Pittsburgh and Elkhorn bed coals were also used. The first objective was to agglomerate the ore with sufficient low temperature coke to provide carbon for reduction, i.e., in the range from 10 to 25 pct. This was accomplished by preheating the ore, mixing with pulverized coking coal, and completing the coal carbonization in a plain steel rotating retort. The pilot retort, as it is now constituted, is shown by diagram in Fig. 1 and photograph, Fig. 2. Ore is fed into the upper kiln by a screw; it is heated to 900° to 1100°F by direct flame and it is then discharged into an insulating hopper from which it goes

Jan 1, 1956

By A. Bauer, P. Calder, N. H. Carr, G. R. Harris

Since both rotary and jet piercing drills are used by the Iron Ore Co. at Smallwood, it is often desirable in planning to know in which regions of the orebody or new orebodies a particular drill will be the most economic. This makes it necessary to establish a correlation between drillability and pierceability and some physical rock properties. For rotary drills a good correlation was found with penetration rate and grinding factor index. The jet piercers were found to have a reciprocal relationship in the sense that the best rotary ground was the worst jet ground and vice versa. It is also indicated how an economic comparison could be made using these penetration rate versus grinding factor index curves, the hole size distribution curves for single pass and chambered holes and the mine distribution curve for grinding factor index. A discussion is presented on the fuel oxygen ratios to be used in jet piercing and on the site gas sampling and analysis which has been used to set up the drills. The fuel has been cut back so that stoichio-metric conditions exist, carbon monoxide is drastically reduced and pop-up or exploding holes eliminated. No decrease in penetration rate has been observed contrary to the published results of previous workers. The blasting procedure and results at Smallwood are discussed and the operation of Iron Ore Co.'s slurry pump-mix truck is also described briefly. Smallwood mine is part of the Iron Ore Co.'s Carol Lake operation and is situated in Labrador, 240 miles north of Sept-Iles, Quebec. Last year 15 million tons of crude ore were crushed to yield 6.3 million tons of concentrate and pellets. This year the figures will be 17 million tons of crude and 7% million tons of concentrate and pellets which is the full plant capacity. Carol Lake ores consist primarily of specularite and magnetite mixed with quartz. For convenience the ore has been split-into the following classifications depending on the percentage of magnetics in the sample, shown in brackets: specularite (0 to 10%), specularite-magnetite (10 to 20%), magnetite- specularite (20 to 30%), magnetite (>30%). The order of classification also represents the order of increasing grinding difficulty - the specularite generally being the easiest and the magnetite the hardest. The orebody also contains a small percentage of waste materials consisting of limonite carbonate, quartz carbonate and quartz magnetite. The first two materials are among the softest in the mine, generally softer than the specularite, and the quartz magnetite is amongst the hardest. The bulk of the material in the mine is of the specularite-magnetite and magnetite-specularite classifications. As a result of test drilling at Smallwood in 1960 with rotary, jet and percussion drills, the Iron Ore Co. purchased four JPM-4 jet piercers for the bulk of production drilling and set up an oxygen plant to supply 20 tons of oxygen per day. This oxygen is sufficient for two machines operating full time and one part time. In addition, there are two 50-R, one 60-R and one 40-R machines in use. The benches are 45 ft high and 50 ft holes are generally drilled. JET DRILLING At the onset of jet drilling in the late fall of 1962, two major problems were encountered: 1) freezing due to winter operations; experience and the use of heat at more places, such as the rotary head, has eliminated this,'" and 2) exploding or "popping" drilled holes; this happened frequently (several holes "popping" each day) and was the cause of two lost time accidents. In one instance a hole was being measured with a tape which fell down the hole causing it to "pop." Safety glasses though pulverized saved the wearer's eyesight. Various methods were then employed to detonate the holes before measuring or loading (dropping lighted rags of fusees down, or sparking across a spark gap). These methods were time consuming and far from completely successful. Consideration was given to the fuel oxygen ratio on the machines and what this would produce in the way of product gases. A fuel oxygen weight ratio of 0.35 which was quite oxygen negative was being used. Theoretically appreciable carbon monoxide would be produced at this fuel oxygen ratio. On the close down procedure of the jet which calls for low oxygen after flame out, oxygen would be left in the hole along with this carbon monoxide. This is an explosive mixture. The fuel oxygen ratio was cut back to stoichiometric

Jan 1, 1967

Jan 1, 1968

By C. A. Bruch, J. F. Duffey

On the basis of metallographic and cooling-rate studies of 15 U-Zr alloys, a new version of the 6 phase region of the U-Zr phase diagram is proposed. IN several published diagrams of U-Zr alloy system:' there is good agreement that at elevated temperatures complete solid solubility exists between y uranium and ß zirconium. Similarly, there is reasonably good agreement concerning the uranium-rich and zirconium-rich ends of the diagram. However, there is no agreement concerning the nature of the diagram at intermediate compositions and at temperatures below about 650°C. The early work of Saller et al.8 hows an intermediate phase, 6. In a later diagram by Saller and Rough' shown in Fig. 1, the d phase field is drawn with dotted lines, indicating doubt that this phase exists. The diagram of Summers-Smith2 does not show the d phase. More recently Holden and Seymour' have shown that in the composition range 40 to 60 wt pet Zr, the high-temperature ? phase, which is body-cen-tered-cubic, transforms to an ordered structure, 8. They found that the order-disorder transformation occurs between 595° and 610°C, and presented a diagram based on the study of four different alloy compositions. Most recently Saller et a1.5 presented a new diagram which differs with respect to the composition limits of the 8 field from the others proposed by these authors. The purpose of the present investigation was to determine the boundaries of the d phase field. Experimental Procedures and Results Alloys—Buttons, weighing 80 g of 15 different alloy compositions were prepared by arc melting Mal-linckrodt uranium and iodide-process zirconium in a water-cooled crucible. A controlled atmosphere of argon and helium was maintained in the furnace. Prior to making each button, a sacrificial button of zirconium was melted to increase the purity of the furnace atmosphere. Each alloy was then melted six times to improve its homogeneity. Subsequently the alloy buttons were jacketed in copper and hot rolled to slabs at 775°C. From these slabs, specimens were machined for chemical, thermal, and metallographic analyses, Table I gives both the estimated chemical composition of the alloys, and the values which were obtained by analysis. The oxygen contents varied from 0.013 to 0.032 pet, nitrogen from 0.0014 to 0.014 pet, and carbon from 0.0013 to 0.011 pet. The purity of the alloys ranged from 99.947 to 99.975 pet. Thermal Analysis—The specimens for thermal analysis were blocks 11/4 x 1/4 x % in. The bead of a calibrated thermocouple was placed between two of these blocks and molybdenum wire was wrapped around the assembly. Each assembly was sealed in a quartz capsule having an argon atmosphere. The capsule was placed inside a refractory crucible which was heated in a furnace. Using a method described by Smith,' the emf of a differential thermocouple, with junctions inside and outside of the refractory crucible, was used to activate the

Jan 1, 1959

By H. J. Booss

THERE is a considerable lack of data on thermody-namic properties of hard-metal alloys. Only two papers 1,2 give mean values of specific heat in an unknown temperature range; more recently the author3 gave more detailed information on the mean specific heat in the temperature range from 20" to -190° C.. EXPERIMENTAL 1) Method—Experimental procedure followed a method suggested by Oelsen and coworkers.4 It requires samples of some 100 g of weight. The time of measurement is prolonged (30 min) but one run allows the measurement of a lot of positions on the heat-content curve. Results4 were found to be in good agreement with "best values" given by kelley,5 Kubaschewsky and Evans,6 etal.

Jan 1, 1960

ALTHOUGH the refining period of the heat is generally defined as starting after the charge has been completely melted, it may more properly be considered as beginning with the first efforts to facilitate the shaping up of the slag and the making of corrective additions for the control of slag or metal composition. Such actions may be initiated during the latter half of the lime boil. The early part of the refining period may, then, in essence overlap the latter part of the melting period. The primary aims of the refining period are: (1) to reduce phosphorus and sulfur from the steel bath to levels safely below the maximum contents specified; (2) to eliminate carbon to a specified level as rapidly as possible and still allow time for proper conditioning of the slag and attainment of the necessary bath temperature; and (3) to have the heat ready for tapping or furnace deoxidation, with slag in the proper physical and chemical condition, and with carbon and oxygen contents and the temperature of the steel at the proper levels for the composition and grade of steel being produced. The particular conditions that fulfill these aims are distinctly different, depending upon whether the steel is to be finished according to fully killed. semikilled, or rimming practice and also depending upon the carbon range specified. Regardless of the type of charging practice employed, the object of the refining period is to produce repeatedly the desired finishing and tapping conditions for the grade of steel being produced. The variations and proportions of raw materials used in the charge may cause some variations in the degree of control required during refining, but not in the method of control. The refining period can therefore be discussed from a viewpoint largely independent of charging and melting practice. SHAPING UP THE SLAG In the first helper's vocabulary, refining practice consists in

Jan 1, 1951

By E. N. Harshman

Uranium mining and milling are rather new industries in Wyoming and South Dakota, but, in the past 15 years, ore valued at more than $400,000,000 has been mined and milled in the region. The major uranium deposits are in structural and/ or erosional basins or on the flanks of uplifts. The principal host rocks are medium- to coarse-grained sandstones that were deposited in continental or brackish-water environments and were derived in large part from the granitic cores of the uplifts and the sedimentary rocks that flank the cores. The ages of the host rocks range from Cretaceous to Miocene, but more than 95 per cent of the known reserves in the region are in rocks of early Eocene age. The bulk of the ore in the region is unoxidized and lies below the water table; some oxidized ore has been mined in the Powder River Basin and Black Hills districts. The unoxidized ore comprises pyrite, uraninite and/ or coffinite, marcasite, hematite, jordisite(?), and selenium. Minerals in the oxidized ore include hydrous uranium carbonates, phosphates, and sulfates and hydrous uranium and/ or vanadium silicates. The deposits are in the form of ore rolls that contain from a few hundred to a few hundred thousand tons of ore, ranging in grade from 0.1 per cent to 1.0 per cent U3O8. The rolls are at the margins of large tabular bodies of sandstone that has been altered by the orebearing solutions. The deposits are believed to have resulted from the interaction of an alkaline; oxidizing, ore-bearing ground water and a reducing environment. Exploration guides include the spatial relations of ore to altered sandstone, favorable lithology in the host rock, the content of certain elements and/ or compounds in ground water, and the relation of deposits to major paleodrainages.

Jan 1, 1968

Discussion of the paper of Dorsey A. Lyon and Robert M. Keeney, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 80, August, 1913, pp. 2117 to 2149. C. D. WOODWARD, Butte, Mont.:-We constructed a small blast furnace, and used first carbon electrodes and an alternating current of about 50 to 75 volts. We were able to smelt the material which was fed to the furnace, but we did not carry on experiments far enough to see just exactly what the power consumption was and compare it with the amount of material treated. We found that the blast seemed to help materially in reducing our charge and cutting down our power consumption. There were several other experiments tried at the time, and I do not call to mind now just what they were. We were trying to do away with the carbon electrode and replace it with an iron one, and it also seems to me we tried to use the ore for an electrode; but I believe that the electric furnace in the reducing end is simply a question of British thermal units per kilowatt-hour compared with British thermal units in a pound of coke. Now, if a pound of coke costs us 0.5 c. and a kilowatt-hour costs us in the neighborhood of 1.5 c., I think there is a big advantage in using coke instead of the electrical current for copper reducing. We tried steam, and a number of other methods, to throw copper down, but it has been some time ago and I am not very familiar with them now. The outlook of the experiments did not seem to be very promising, and we took it more as a thermal problem than an electrical one. PROF. JOSEPH W. RICHARDS, South Bethlehem, Pa.:-Mr. Woodward has spoken of the question as a thermal problem. I would call attention to the fact that electric furnaces usually utilize the heat of the electric current at from four to ten times the efficiency with which the heat generated by fuel is utilized; so it will not do simply to compare by thermal units generated. Your total thermal units may cost much less from coke than from electricity, yet you will find the electrically generated thermal units utilized in a properly designed furnace from three to ten times more efficiently than in the combustion furnace. You must make that allowance is comparing the cost of thermal units generated electrically and thermal units from coke.

Jan 11, 1913

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members) Member, Graduate Colorado School of Mines. Four years' experience in West and Northwest. Two years with American Smelting and Refining Co. Wishes to join field party on geological work, mining or areal, where opportunity will be given to be of direct assistance to chief of party in solution of field problems. Age, 26. Unmarried. At liberty June 1. No. 342. Member, technical graduate, aged 30, with' 7 years' experience in concentrating and mining, desires a position of authority with reliable company. At present employed. No. 343. Member. Ambitious, energetic, tactful engineer, college graduate, married, aged 30, desires location with a large coal mining organization. Seven years with present employers -n middle west; has had broad experience in the past eight years on examination, development and construction; successful record in handling men. Position must carry responsible work and a future. Will go anywhere for proper opportunity. Exceptional references as to reliability, character and capacity for work. No. 344.

Jan 3, 1917

By J. P. Hirth, G. M. Pound

The flux of evaporation J from {loo) , {111), and (110) planes of silver single crystals and from poly crystalline specimens was measured at 744°C under a high vacuum using a time average weight loss method. The evaporation coefficient a was computed from the measured flux and vapor pressure data through the relationship J = aPe/21rmkT. The evaporation coefficients for the close packed planes and the poly crystalline specimens were found to be about 0.4 providing tentative confirmation of the theoretical limiting law for evaporation of metal crystals, a = 73(P/Pe) + % . The (110) planes faceted to form (111) planes, resulting in a greater evaporating area and larger a . The evaporation morphology of the plane surfaces and the surfaces of spherical single crystals is described in some detail. RECENTLY a detailed theoretical analysis of the mechanism and kinetics of metal crystal evaporation was made.1'2 A mechanism for vaporization involving the recession of monatomic ledges across a metal surface was deduced, and evaporation rate equations were derived by considering the dynamics of these ledges. In most metals, the process of evaporation is one of dissociation of atoms from ledges, surface diffusion, and desorption. The gross vaporization rate is controlled by the surface diffusion and desorption rates. It was shown that the monatomic ledges, under the action of surface diffusion gradients, tend to assume a terminal velocity and spacing. Further, it was shown that crystal edges and grain boundaries are a ready source for monatomic ledges. In the case of evaporation of large, perfect crystals with clean, low-index surfaces, the kinetic treatment1 leads to a limiting law for crystal evaporation: where J is the gross flux of vaporization, a is the evaporation coefficient, Pe the equilibrium vapor pressure, m the atomic mass, k Boltzmann's constant, T the absolute temperature, and P the actual pressure of vapor over the crystal surface. Imperfections such as grain boundaries, pores, cracks, and macroscopic steps should have the effect of causing positive departures from this limiting law. Such an imperfection is a source for monatomic ledges, which, near their origin, are closely spaced and thus give rise to higher evaporation rates there. However, under many experimental conditions,' this effect should be negligible due to the relatively low concentration of imperfections. In general, a more important cause of positive departure should be screw dislocations, and the effect of these has been considered in some detai1.2,3 Monatomic ledges emanate from points where the surface is intersected by a dislocation with a screw component normal to the surface. The dynamics of ledges arising from a screw dislocation are similar to those of ledges arising from a crystal edge. There is a perturbed region near the origin where the monatomic ledges are, under certain experimental conditions, closely spaced and the

Jan 1, 1960

By William Hurst, A. F. van Everdingen

For several years the authors have felt the need for a source from which reservoir engineers could obtain fundamental theory and data on the flow of fluids through permeable media in the unsteady state. The data on the unsteady state flow are composed of solutions of the equation Two sets of solutions of this equation are developed, namely. for "the constant terminal pressure case" and "the constant terminal rate case." In the constant terminal pressure case the pressure at the terminal boundary is lowered by unity at zero time, kept constant thereafter, and the cumulative amount of fluid flowing across the boundary is computed, as a function of the time. In the constant terminal rate case a unit rate of production is made to flow across the terminal boundary (from time zero onward) and the ensuing pressure drop is computed as a function of the time. Considerable effort has been made to compile complete tables from which curves can be constructed for the constant terminal pressure and constant terminal rate cases, both for finite and infinite reservoirs. These curves can be employed to reproduce the effect of any pressure or rate history encountered in practice. Most of the information is obtained by the help of the Laplace transformations, which proved to be extremely helpful for analyzing the problems encountered in fluid flow. The application of this method simplifies the more tedious mathematical analyses employed in the past. With the help of Laplace transformations some original developments were obtained (and presented) which could not have been easily foreseen by the earlier methods. INTRODUCTION This paper represents a compilation of the work done over the past few years on the flow of fluid in porous media. It concerns itself primarily with the transient conditions prevailing in oil reservoirs during the time they are produced. The study is limited to conditions where the flow of fluid obeys the diffusivity equation. Multiple-phase fluid flow has not been considered. A previous publication by Hurst' shows that when the pressure history of a reservoir is known, this information can be used to calculate the water influx, an essential term in the material balance equation. An example is offered in the literature by Old² in the study of the Jones Sand, Schuler Field, Arkansas. The present paper contains extensive tabulated data (from which work curves can be constructed), which data are derived by a more rigorous treatment of the subject matter than available in an earlier publication.' The application of this information will enable those concerned with the analysis of the behavior of a reservoir to obtain quantitatively correct expressions for the amount of water that has flowed into the reservoirs, thereby satisfying all the terms that appear in the material balance equation. This work is likewise applicable to the flow of fluid to a well whenever the flow conditions are such that the diffusivity equation is obeyed. DIFFUSITY EQUATION The most commonly encountered flow system is radial flow toward the well bore or field. The volume of fluid which flows per unit of time through each unit area of sand is expressed by Darcy's equation as where K is the permeability, the viscosity and aP/ar the pressure gradient at the radial distance r. A material balance on a concentric element AB, expresses the net fluid traversing the surfaces A and B, which must equal the fluid lost from within the element. Thus, if the density of the fluid is expressed by p, then the weight of fluid per unit time and per unit sand thickness, flowing past Surface A, the surface nearest the well bore, is given as The weight of fluid flowing past Surface B, an infinitesimal distance 6r, removed from Surface A, is expressed as

Jan 1, 1949

By A. F. van Everdingen, William Hurst

For several years the authors have felt the need for a source from which reservoir engineers could obtain fundamental theory and data on the flow of fluids through permeable media in the unsteady state. The data on the unsteady state flow are composed of solutions of the equation Two sets of solutions of this equation are developed, namely. for "the constant terminal pressure case" and "the constant terminal rate case." In the constant terminal pressure case the pressure at the terminal boundary is lowered by unity at zero time, kept constant thereafter, and the cumulative amount of fluid flowing across the boundary is computed, as a function of the time. In the constant terminal rate case a unit rate of production is made to flow across the terminal boundary (from time zero onward) and the ensuing pressure drop is computed as a function of the time. Considerable effort has been made to compile complete tables from which curves can be constructed for the constant terminal pressure and constant terminal rate cases, both for finite and infinite reservoirs. These curves can be employed to reproduce the effect of any pressure or rate history encountered in practice. Most of the information is obtained by the help of the Laplace transformations, which proved to be extremely helpful for analyzing the problems encountered in fluid flow. The application of this method simplifies the more tedious mathematical analyses employed in the past. With the help of Laplace transformations some original developments were obtained (and presented) which could not have been easily foreseen by the earlier methods. INTRODUCTION This paper represents a compilation of the work done over the past few years on the flow of fluid in porous media. It concerns itself primarily with the transient conditions prevailing in oil reservoirs during the time they are produced. The study is limited to conditions where the flow of fluid obeys the diffusivity equation. Multiple-phase fluid flow has not been considered. A previous publication by Hurst' shows that when the pressure history of a reservoir is known, this information can be used to calculate the water influx, an essential term in the material balance equation. An example is offered in the literature by Old² in the study of the Jones Sand, Schuler Field, Arkansas. The present paper contains extensive tabulated data (from which work curves can be constructed), which data are derived by a more rigorous treatment of the subject matter than available in an earlier publication.' The application of this information will enable those concerned with the analysis of the behavior of a reservoir to obtain quantitatively correct expressions for the amount of water that has flowed into the reservoirs, thereby satisfying all the terms that appear in the material balance equation. This work is likewise applicable to the flow of fluid to a well whenever the flow conditions are such that the diffusivity equation is obeyed. DIFFUSITY EQUATION The most commonly encountered flow system is radial flow toward the well bore or field. The volume of fluid which flows per unit of time through each unit area of sand is expressed by Darcy's equation as where K is the permeability, the viscosity and aP/ar the pressure gradient at the radial distance r. A material balance on a concentric element AB, expresses the net fluid traversing the surfaces A and B, which must equal the fluid lost from within the element. Thus, if the density of the fluid is expressed by p, then the weight of fluid per unit time and per unit sand thickness, flowing past Surface A, the surface nearest the well bore, is given as The weight of fluid flowing past Surface B, an infinitesimal distance 6r, removed from Surface A, is expressed as

Jan 1, 1949

By R. W. Gurry, L. S. Darken

The solubility of cementite in austenite is computed by thermodynamic methods from the observed solubility of graphite. It is found that the solubility of cementite is greater than that of graphite in the entire austenite temperature range. Thus the prior discrepancy between this portion of the phase diagram and the observed metastability of cementite is partially resolved. FOR several years it has been apparent that a serious discrepancy exists in certain observations pertaining to the Fe-C system. Direct experimental data indicate: 1-That the curve representing the solubility of graphite in austenite'" crosses that for cementite4 at about 945°C as shown in Fig. 1. 2— That graphite and austenite saturated therewith are stable1 relative to cementite at all temperatures between the eutectoid, about 723°C, and the eutectic, about 1153°C. These observations are mutually incompatible in view of a well-known consequence of the second law of thermodynamics, namely, that the stable phase (presumably graphite at all temperatures) has a lower solubility than the metastable phase (presumably cementite). Hence either 1 or 2 above must be in error; either the measured solubility of graphite or of cementite, or the observation as to the stability of graphite, is in error. Our present purposes are: 1—To collate the available data on cementite and prepare a table of HO — HO° and of (Fa— HO°)/T. This tabular method seems the best and most convenient way to represent the heat and free energy of formation. 2—To determine whether the measured solubilities of cementite and graphite in austenite are in accord with the above table and the measured thermodynamic properties of austenite, in order to resolve, if possible, the existing paradox of these two solubilities. Enthalpy of Cementite The enthalpy of cementite at 273 °K, H279 — HOcem, was computed by integration of the low temperature heat capacity as measured by Seltz, McDonald, and Wells" 68" to 298 °K) and as given by the Debye functions recommended by them (0" to 68°K); the result is included in Table I. At higher temperature HCem — H,,"" is given by Kelley who used the data of Naeser7 (298" to 1037°K) and of Umino8,9 (273° to 1923°K). We have recalculated Hcem — H273 cem from the data of UminoO in the following way. In the equilibrated alloy at temperature the weight fraction of cementite Pct c -Pct cr is PctC -PctCr designated f(C), and the

Jan 1, 1952

By R. E. Lindstrom, D. G. Peterson, H. J. Heinen

Alkaline alcohol solutions were investigated by the Federal Bureau of Mines for improving the desorption rate of gold and silver from metal-laden activated carbon generated in gold processing circuits. Factors affecting the desorption, such as temperature, alcohol content, type of alcohol, and alkalinity, were studied. Nearly complete metal desorption was obtained in 5 to 6 hr at 80º C using a solution containing about 20 vol-pct alcohol and 1 pct sodium hydroxide. Sodium sulfide was shown to be effective for selectively precipitating silver from the carbon strip solutions, thereby providing a means for producing high- purity gold by subsequent electrolysis.

Jan 1, 1976

By Gerald Edmunds

Although the phenomenon of season cracking is still imperfectly understood, there seems to be ample evidence that season cracks are propagated by the combined action of corrosion and a stress of either internal (residual) origin or external origin. The factors that influence season cracking may therefore be grouped according to corrosive media, nature of stress, and character of the material. Thus the important mass of evidence pointing to ammonia as the most frequently active corroding agent causing season - - cracking of brass has naturally led to the development of laboratory tests of a moderately accelerated character based upon ammonia together with auxiliary agents such as air, water vapor, and carbon dioxide as the corroding agent. Similarly, the knowledge that stress must be present has led to the use of externally applied and therefore accurately measurable stresses in laboratory testing. A companion paper(^)^ to the present one discusses the development of these test methods in our laboratories. The present paper discusses data bearing on factors concerning the nature of stress such as its magnitude and direction of application. It also deals extensively with the character of the brass, particularly in regard to the copper-zinc ratio and the structure as developed by mechanical work-

Jan 1, 1945

By I. W. Walling, F. B. Plummer

Bastin and others have demonstrated the presence of sulphate-reducing bacteria in oil wells producing salt water. Analyses show that at 125°F. bacteria alone reduce sulphates in East Texas salt water by only 3 per cent in 30 days, forming principally hydrogen sulphide and sodium or calcium hydroxide. The hydrogen sulphide reacts with soluble iron compounds to produce iron sulphide in the absence of oxygen, and ferric hydroxide where oxygen and air are present. Where iron or other metals and iron sulphide are already in the water containing bacteria, I00 per cent reduction of the sulphates is complete in 30 days or less; where magnesium is present, reduction is complete in 15 days. The effects of changes in temperature, of different bactericides, and of concentration of bactericides on sulphate reduction are described in detail and illustrated by tables and curves. The significance of sulphate reduction on corrosive properties of oil-field water is briefly discussed. Chemistry of East Texas Oil-field Water The chemical composition of the water in the East Texas field salt-water disposal pits is shown in Table I. This salt water corrodes pipes, pumps, and steel tanks excessively, principally because of its content of oxygen, hydrogen, sulphide, and carbonic acid. The carbonates in the water when exposed to air tend to give up carbon dioxide and to precipitate calcium carbonate in large quantities. This forms coatings in tanks, settling pits, and ditches, and soon, unless removed by acid treatment, will effectively clog an injection well and reduce the flow of water back into the ground. The iron compounds in the water, most of which are dissolved from tanks and pipes, are in the ferrous form, and when exposed to the air are oxidized from soluble ferrous carbonate to insoluble ferric hydroxide, resulting in the precipitation of a gelatinous precipitate that will clog oil-field sands effectively: 2Fe(HCO3)2 + O + H2O -> 2Fe(OH)3 + 4CO2 The sulphates in strong sulphate-bearing water may be attacked by swarms of sulphate-reducing bacteria and more hydrogen sulphide may be produced. The hydrogen sulphide reacts with soluble minerals in the water to form black sludges. A knowledge of the chemistry of each reaction in oil-field water is important to the oil-field engineer, since means must be devised to prevent the formation of harmful precipitates that clog injection wells and to prevent corrosion of tanks by harmful products of biochemical processes. Methods of Treating Water before Injection into Ground* The open system of handling the waste salt water in the East Texas field consists of aerating and chemically treating the water to precipitate the unstable iron,

Jan 1, 1946

By F. B. Plummer, I. W. Walling

Bastin and others have demonstrated the presence of sulphate-reducing bacteria in oil wells producing salt water. Analyses show that at 125°F. bacteria alone reduce sulphates in East Texas salt water by only 3 per cent in 30 days, forming principally hydrogen sulphide and sodium or calcium hydroxide. The hydrogen sulphide reacts with soluble iron compounds to produce iron sulphide in the absence of oxygen, and ferric hydroxide where oxygen and air are present. Where iron or other metals and iron sulphide are already in the water containing bacteria, I00 per cent reduction of the sulphates is complete in 30 days or less; where magnesium is present, reduction is complete in 15 days. The effects of changes in temperature, of different bactericides, and of concentration of bactericides on sulphate reduction are described in detail and illustrated by tables and curves. The significance of sulphate reduction on corrosive properties of oil-field water is briefly discussed. Chemistry of East Texas Oil-field Water The chemical composition of the water in the East Texas field salt-water disposal pits is shown in Table I. This salt water corrodes pipes, pumps, and steel tanks excessively, principally because of its content of oxygen, hydrogen, sulphide, and carbonic acid. The carbonates in the water when exposed to air tend to give up carbon dioxide and to precipitate calcium carbonate in large quantities. This forms coatings in tanks, settling pits, and ditches, and soon, unless removed by acid treatment, will effectively clog an injection well and reduce the flow of water back into the ground. The iron compounds in the water, most of which are dissolved from tanks and pipes, are in the ferrous form, and when exposed to the air are oxidized from soluble ferrous carbonate to insoluble ferric hydroxide, resulting in the precipitation of a gelatinous precipitate that will clog oil-field sands effectively: 2Fe(HCO3)2 + O + H2O -> 2Fe(OH)3 + 4CO2 The sulphates in strong sulphate-bearing water may be attacked by swarms of sulphate-reducing bacteria and more hydrogen sulphide may be produced. The hydrogen sulphide reacts with soluble minerals in the water to form black sludges. A knowledge of the chemistry of each reaction in oil-field water is important to the oil-field engineer, since means must be devised to prevent the formation of harmful precipitates that clog injection wells and to prevent corrosion of tanks by harmful products of biochemical processes. Methods of Treating Water before Injection into Ground* The open system of handling the waste salt water in the East Texas field consists of aerating and chemically treating the water to precipitate the unstable iron,

Jan 1, 1946

ARTHUR CROWFOOT, Morenci, Ariz. (communication to the Secretary*).-In order to set at rest any doubts in regard to the reasons for selecting the Callow pneumatic flotation process for use in the concentrators of the Arizona Copper Co., Ltd., at Clifton and Morenci, I am presenting the following facts gained from the results of test work carried out on the Callow and Cole-Bergman types of flotation machines at Morenci. Prior to the comparative test of merit between the Callow and Cole-Bergman machines, many months' time and a large amount of money had been expended in the development and testing of the Cole-Bergman machine, and it was necessary to decide quickly what make of machine was best to install. The Callow pneumatic flotation process was recommended for installation in our concentrators for the following reasons: The results indicated: 1. That the Callow system made the highest extraction of copper values from the feed treated. 2. That the Callow system was simpler to operate and could he operated it a lower cost. 3. That the Callow system operated with a lower air pressure. (The question of the actual power consumption of the two types of machines was not definitely settled at this time.) During the official test period the Callow flotation apparatus showed an additional recovery of from 1 to 1.5 lb. of copper per ton more than the Cole-Bergman machine, this difference being maintained by further treatment of the tailing from both machines. The simplicity of the operation of the Callow flotation system is one of its notable features, two operators per shift being able to handle 90 standard cells and blower equipment.

Jan 7, 1917

By F. R. Brotzen, A. R. Troiano, E. L. Harmon

Precipitation processes leading to drastic property changes are a frequent occurrence in titanium alloys containing large amounts of the retained high temperature P phase. In order to establish the kinetics and nature of these precipitation processes, a series of Ti-V alloys was studied. Time-temperature-transformation diqgrams were obtained for 12.5 and 15 pct V-Ti alloys. These diagrams consisted of two intersecting C-shaped curves: one in the high temperature region for the euilibrium transformation P +u+P, and another at lower temperatures depicting the formation of the meta-stable transition phase, o. Presence of the transition phase retarded the precipitation of the equilibrium a phase. Deformation of retained P resulted in the formation of the o phase. Reversion and retrogression phenomena of the transition phase were observed. A negative temperature coefficient of resistance was found in quenched alloys containing from 15 to 20 pct V. CERTAIN titanium-base alloys can be heat treated to produce appreciable changes in properties. For example, remarkably high hardness values may be obtained by aging or isothermal quenching treatments. Most of the information available to date on the hardening of titanium-base alloys has been systematized recently in an article by L. D. Jaffe.' It was pointed out by that author that the hardening was the result of the decomposition of the retained j3 phase to the equilibrium constituents, a and p, and that this decomposition had many of the characteristics of an age-hardening reaction. Recent work by Frost et al.' 3 has contributed much to the fundamental understanding of the hardening mechanism in titanium-base systems. These authors established the presence of a transition phase in the transformation from j3 to a + j3, which they designated o. The transition phase, in their opinion, was at least partially responsible for the hardening and embrittling effects which accompanied low temperature aging. The present investigation of the mechanism and kinetics of the hardening reaction was carried out for the Ti-V system. Ti-V alloys were ideally suited for a study of the decomposition of j3, since age hardening was known to occur readily in this system." Moreover, no intermetallic compounds occur in this system, Fig. 1, thus simplifying the interpretation of the results. Material and Procedure Alloys containing 12.5 and 15 pct V were prepared by Battelle Memorial Institute from iodide titanium furnished by Watertown Arsenal and vanadium of 99.8 pct purity. Ingots of 8 Ib each were prepared by arc melting in an inert atmosphere with a tungsten electrode and water-cooled copper crucible. Each of the ingots was melted once, forged at 1600°, and rolled at 1400°F. Following this, the ingots were remelted, forged, and then rolled to % in. sq bars, which were subsequently grit blasted, pickled, and wire brushed. Another set of alloys containing nominally 17.5 and 20 pct V was produced by the Research Div., New York University. These alloys were arc melted in an inert atmosphere in lots of 20 g each. Heat-Treating Procedure: Whenever feasible, specimens were heat treated in high vacuum resistance furnaces at pressures below 5x10." mm of Hg. Aging and isothermal quenching treatments were generally carried out in salt baths. Specimens were not attacked by the salt, provided the tempera-

Jan 1, 1956

By W. A. Backofen, B. C. Wonsiewicz

The Plasticity transition in magnesium was studied by plane-strain compression of single crystals and polycrystalline material at temperatures from about 20" to 307°C. Reduction of single crystals along the c axis was accommodated by twinning on {1011) and retwinning on (10 12}, followed by basal shear in the doubly twinned volume. Deformation in that mode can result in sufficient independent shears for arbitrary shape change. Fracture in c axis compression, below about 100°C, has been related to excessive shear caused by unloading from the stress for {1011} twinning (-50 ksi at 20°C) to that for slip within the twin (-3 ksi); ductility follows from heating because the stress difference is lowered and the twin volume, in which elastic strain energy is dissipated on unloading, is increased. The stress for (1011) twinning is strongly temperature-dependent but not given by a critical resolved shear stress law. The latter is attributed to the influence of stress concentration from prior intersecting shear on nonbasal planes, the former to the temperature dependence of the preliminary slip. THE basic symmetry of hcp crystals has the effect of limiting the number of independent slip systems and making twinning an important deformation mechanism. The general result in wrought polycrystalline aggregates is a more or less sharply developed texture (or preferred orientation) which underlies a strong anisotropy in mechanical behavior. Knowing how the one influences the other is essential background for the use of such materials. Magnesium was of interest in this work because of the unexplained plasticity transition that it undergoes somewhere in the neighborhood of 200°c.''~ At lower temperatures plastic deformation before fracture in polycrystalline material is limited, while at higher temperatures extensive deformation is possible. The transition temperature commonly determines the lower limit of the range in which magnesium is worked. The limited ductility can be traced to a lack of independent crystallographic shears. A minimum of five are required for arbitrary shape change.' Around room temperature, however, slip on all known systems provides only four.' In each case, the slip direction is in the (0001) basal plane so that slip does not allow strain along the c axis. With increasing temperature, more slip occurs on the ( 1011) pyramidal plane and the ( 1010) prism plane but without change in direction.'?' Thus, that development alone cannot explain the transition temperature.

Jan 1, 1968